A tandem type image forming apparatus is known in which a plurality of photosensitive drums is arrayed in line in a horizontal direction. Laid-open Japanese Patent Application publication No. 2003-29532 discloses such an image forming apparatus provided with a toner container in which a toner chamber containing a toner as a developing agent is disposed below a photosensitive drum.
In such a conventional image forming apparatus, stabilized toner supply to the photosensitive drum may be difficult to achieve, since the toner in the toner chamber must be conveyed upward against gravity of the toner. According to the device described in JP 2003-29532 publication, a toner agitator scoops the toner, and the scooped toner is accumulated on a toner accumulation plate provided at an upper portion of the toner container. Then the accumulated toner is supplied to a toner supply roller, and is then supplied to the photosensitive drum through a developing roller.
However, the toner agitator is out of contact from an inner surface of the toner chamber. Therefore, the toner carried on the toner agitator may be dropped out of the agitator and fallen into the toner chamber through a gap between the toner agitator and the inner surface. In other words, desirable delivery of the toner from the lower portion (toner chamber) to the upper portion (toner accumulation plate) cannot be performed.